Mallet finger is a commonly used term in medical practice for a closed rupture of the extensor tendon at the distal interphalangeal joint of a finger (FIG. 1). Mallet finger is frequently a result of a trivial injury and is usually minimally painful. The injury is typically caused by forced flexion of the distal interphalangeal joint of a finger, resulting in stretching and rupture of the extensor tendon, usually at or near its insertion on the dorsal lip of the distal phalanx. On examination patients have a characteristic flexion deformity of the finger at the distal interphalangeal joint (FIGS. 2-5). X-rays are usually negative, although on occasion there may be a small fracture of the distal phalanx in the location of the tendon's insertion, indicating that the extensor tendon over the joint has pulled off a piece of bone.
A splint typically needs to be worn for a minimum of six weeks (continuously, without removal or change) for healing of the tendon to occur. Multiple splint mechanisms have been developed to treat mallet finger, including stack splints, oval 8 splints, and simple alumina foam splints. Existing splint solutions are largely unsatisfactory for several reasons. First, they require that the finger stay dry, precluding washing or showering unless a watertight “bag” is worn over the area. If moisture accumulates under the splint, problems can arise with maceration of the skin under the splint. Second, if the fit of the splint is too loose, the finger will have a persisting flexion deformity at the distal interphalangeal joint, resulting in treatment failure. Moreover, even a well performed splint change during the course of treatment may disrupt the healing process if even a small amount of flexion occurs, setting treatment back substantially. Surgery may not be effective for treating a mallet finger injury and increases the potential for complications; in addition, even surgical treatment is usually combined with splinting.
Current splint solutions frequently fall off, become loose, may cause pressure sores or skin maceration, and interfere with daily activities and personal hygiene. Accordingly, new treatment modalities are needed to solve one or more of these problems and to effectively treat a mallet finger injury or other injury to tendon, ligament and/or bone in a digit (e.g., a boutonniere deformity, a volar plate fracture or dislocation, a fracture of the middle phalanx, fracture of the proximal phalanx of the thumb).